Polymerization of beta-pinene



United States Patent Office 1 2,932,631 POLYMERIZATION F fl- PINENE Alfred L. Rummelsburg, Chadds Ford, Pa., assignor to Hercules Powder Company, Wilmington, Del., a corporation of Delaware No Drawing. Application December 26, 1957 Serial No. 705,131

3 Claims. (Cl. 260-933) This invention relates to the polymerization of 18-pinene and more particularly to the production of hard resins from polymerization treatment of a mixture of aand fl-pinene.

It is Well known that fi-pinene can be polymerized to hard resins by contacting fi-pinene with a Friedel-Cratts catalyst, and that when a-pinene is present, it polymerized to a'balsam and greatly softens the resin product. When the pinene cut contains more than about a-pinene, the resins are very soft due to the homopolymerization of the tar-pinene. The prior art catalysts, including the Friedel-Crafts catalysts, are low in selectivity and polymerize other terpenes including a-pinene in pinene cuts containing the B-piuene so that hard resins are obtained only when pinene cuts used contain at least about 75% ,B-pinene.

Now in accordance with the present invention it has 25 been found that fl-pinene is polymerized to a much higher melting resin when the. fl-pineue is contacted with a catalytic amount of an organoaluminum chloride of the formula RAlCl in which R is a hydrocarbon radical.

It has further been found that fi-pinene may be poly- 3o merized even in the presence of up to about 80% upinene with the production of a hard, stable, light-colored resin.

The polymerization process of the present invention is highly selective with respect to polymerization of ;8- a5 pinene. When the process is applied to a B-pinene cut containing also u-pinene, the first B-pinene polymerizes as a homopolymer, but as thepolymerization proceeds and the ratio of available fi-pinene becomes less, the fl-pinene forms a copolymer with u-pinene which is softer than B-pinene homopolymer. However, when the 8-pinene has all polymerized, the a-pinene remaining in contact with the catalysts of this invention is greatly esistant to homopolymerization, and it is possible to stop the polymerization process by destruction of the catalyst and prevent formation of the balsamic rat-pinene polymer. The ratio of fi-pinene homopolymer to ,e-pinene copolymer in a resin obtained by contacting a mixture of B- pinene and tit-pinene with the catalyst of this invention is highest in the first increments of polymer formed and decreases as the ratio of fi-jinene to e-pinene changes during the polymerization process. The highest melting resins are thus obtained from those pinene mixtures in which the fi-pinene content is greatest, but high melting resins may also be obtained by stopping the polymerization before all of the B-pinene has polymerized 2,932,631 Patented Apr. 12, 1960 2 and before a substantial amount of copolymer is prodnced. Using catalysts of the present invention, the polymerization of fl-pinene to hard high melting resins is possible even with as much as about 80% (it-pinene present in the pinene cut of fl-pinene.

The reaction may be carried out in the presence or absence of an inert hydrocarbon solvent or halogenated hydrocarbon solvent to act as a diluent for the reaction, in which case the catalyst may be dissolved in the solvent, and the catalyst solution and the pinene may then be combined.

The polymerization temperature may be any temperature in the range of about -80 to about: 150 C. The preferred temperature of reaction is in the range of about 5 C. to about C. The rate of polymerization increases with increase in temperature so that one skilled in the art may select a temperature that gives the desired polymer in any selected time interval.

The RAlCl catalyst is generally prepared by the reaction of a halogen substituted hydrocarbon with metallic aluminum but may be prepared by any of the well known.

methods known in the art. While the nature of the hy-- drocarbon radical is not critical, it may be any aryl,

alkyl, or cycloalkyl hydrocarbon radical having up to about 18 carbon atoms. However, it is preferably a lower allcyl, with 1 to 4 carbon atoms. Examples of operable hydrocarbon radicals are: methyl, ethyl, propyl,. butyl,cyclopentyl, cyclopentadienyl, cyclohexyl, phenyl, ancltolyi. The amount of catalyst likewise is not critical andwhile an excess over a catalytic amount may be used, a catalytic amount and less than about 10% is generally used. The catalyst need not be free of impurities to the effective in the process of this invention and may contain in addition R AICI or AIR or other by-products which maybe present.

The process of this invention is more explicitly de' scribed by the following examples in which the parts are parts by Weight.

Examples In the table are set forth details of various runs to show the types of products obtainable by variations within the scope of this invention. In general, the polymerizations were carried out by adding the B-pinene to the catalyst mixture but in runs 5-9 the catalyst mixture was added to the ,B-pinene mixture. Runs 1 and 2 show the use of catalyst containing C H AlCl produced by the reaction of (C H AlCl with TiCl neither of which reagents alone are effective catalysts. Runs 3-7 on the other hand show the use of C H AlCl alone as the catalyst, runs 4 and 8 being blanks to distinguish polymerization of u-pinene from the polymerization of B- pinene alone as well as in a mixture. Runs 9-16 show the use of (C H AlCl in admixture with C H AlCl which mixture is usually called an aluminum sesquichloride as though it were a distinct compound rather than a mixture.

Heptane 5.9

5 9 8 8 27 19. 8 14 l4 18 27 Temp, C. 45 27 45 45 45-80 10-47 10-47 10-47 10-36 24-28 35-40 35-40 0 -07 $2 -67 to 10-49 Time, Hr- 2.25 2.3 2.5 2.5 2 2 2 2 1 5 6 2 5 2.5 2 5 4 3 2 Resin Yield. 50 42 51 2 75 53 7 58 54 21 53 51 4 4 58 M.P., C. (Oapillary) 113-120 108-114 S.P., 0. (Dr p Method) 145 102 110 141 121 134 109 135 131 121 1 Pale brittle resins. i Balsamic resins.

Runs 14 and 15 show that pale hard resins are also obtainable at temperatures as low as -74 C.

The polymerizations are all slightly exothermic and are carried out by any of the procedures known in the art for polymerization of 18-pinene simply by substitution of the catalyst of this invention for the prior art catalyst, and by use of anhydrous reagents in an anhydrous system such as is normally used with water sensitive catalysts such as aluminum chloride. In addition, oxygen, carbon dioxide, and compounds with an active hydrogen such as are known to react with metal alkyls are kept out of the polymerization system. In general, the catalysts of this invention give a paler and harder product than is given by aluminum chloride under the same reaction conditions using equivalent quantities of catalyst even with pure ,B-pinene. Moreover, the C H AlCl acts more selectively on B-pinene in a mixture with u-pinene than does aluminum chloride, or other Friedel-Crafts catalyst of the prior art and as a result pinene of lower fi-pinene content may be subjected to the polymerization reaction using C I-I AlCl for the production of a hard resin. When wpinene is present, the reaction time is selected as a time suflicient for fl-pinene contained therein to polymerize and a longer time which might force slow polymerization of a-pinene is avoided. Timing is a variable readily determined by a preliminary run.

.The catalyst is inactivated at the end of the selected polymerization period for production of the desired resin by reaction with a hydroxyl compound such as water, alcohol or a carboxylic acid. For this purpose, water, methanol, ethanol, formic acid or acetic acid in an amount at least equal molecula'rly to the amount of catalyst and preferably at least three times the molecular amount may be used. The catalyst is then washed out with an aqueous alkali (preferably NaOH) solution and the resin is recovered from the organic layer by distilling off the unreacted pinene and other solvents that may be in which R is the ethyl radical, other. homologsthereof are equally useful but are less readily available and in chemically equivalent amounts are equivalent and may be substituted directly for C H AlCl The resins of this invention find utility in lacquer compositions and as a grim substitute in varnishes the same as fi-pinene polymers of the art.

What I claim and desire to protect by Letters Patent is:

1. The method of preparing a hard, stable, lightcolored resin which comprises contacting B-pinene with a catalytic amount of RAlCl in which R is a hydrocarbon radical selected from the group consisting of the lower alkyl radicals having 1 to 4 carbon atoms at a temperature in the range of about 80 to about 150 C. until polymerization of fi-pinene is effected and separating said resin by distilling off the unreacted pinene.

2. The method of claim 1 wherein C2H5A1C13 is used as'the active catalyst component.v

3. The method of preparing a hard, stable, lightcolored resin which comprises contacting a mixture of alphaand beta-pinene containing at least 20% fi-pinene Witha catalytic amount of RAlCl in which R is a hydrocarbon radical selected from the group consisting of the lower alkyl radicals having 1 to 4 carbon atoms at a temperature in the range of about 80 to about 150 C. until polymerization of B-pinene is eifected, deactivating the catalyst before all of the B-pinene has polymerized,

1 and separating said resin by distilling ofi the unreactcd present. This distillation may be a dry distillation or a steam distillation and is preferably carried out under reduced pressure.

While the examples show the preferred catalyst RAlCl pinene.

References Cited in the file of this patent UNITED STATES PATENTS 2,388,428 Mavity Nov. 6, 1945 2,405,558 Borglin Aug. 13, 1946 2,794,819 Smith June 4, 1957 2,848,472 Cottle Aug. 19, 1958 2,852,544 Nowlinet al. Sept. 16, 1958 FOREIGN PATENTS 538,782 Belgium Dec. 6, 1955 

1. THE METHOD OF PREPARING A HARD, STABLE, LIGHTCOLORED RESIN WHICH COMPRISES CONTACTING B-PINENE WITH A CATALYTIC AMOUNT OF RALCL2 IN WHICH R IS A HYDROCARBON RADICAL SELECTED FROM THE GROUP CONSISTING OF THE LOWER ALKYL RADICALS HAVING 1 TO 4 CARBON ATOMS AT A TEMPERATURE IN THE RANGE OF ABOUT -80 TO ABOUT 150* C. UNTIL POLYMERIZATION OF B-PINENE IS EFFECTED AND SEPARATING SAID RESIN BY DISTILLING OFF THE UNREACTED PINENE. 